Session: 617. Acute Myeloid Leukemias: Biomarkers, Molecular Markers and Minimal Residual Disease in Diagnosis and Prognosis: Poster I
Hematology Disease Topics & Pathways:
Research, Acute Myeloid Malignancies, AML, Translational Research, Diseases, Myeloid Malignancies, Biological Processes, molecular biology, Technology and Procedures, molecular testing
Methods and Results. We screened by RT-PCR, RQ-PCR, capillary electrophoresis and Sanger sequencing 41 genetic markers on 371 RNA and DNA samples, identifying a molecular marker at diagnosis for 247 cases out of the 371 enrolled (67%). As far as gene mutations detected are concerned, we identified 24/371 cases harboring a mutation in exon 12 of NPM1 gene (6.5%), 16/371 a FLT3-ITD mutation (4.3%), and 7 harboring both NPM1 and FLT3-ITD mutations (2%). Moreover, we also found 2 cases having a partial tandem duplication affecting KMT2A gene (2/371, 0.5%), one of them occurring together with a FLT3-ITD mutation. For chromosomal aberrations, we confirmed that t(8;21)RUNX1::RUNX1T1 and inv(16)CBFB::MYH11 are recurrent translocations in pediatric AML, being found in 13.5% (50/371) and 12% (44/371) of cases respectively. Sixty-four (17,3%) AML cases were characterized by a KMT2A fusion with different partner genes, with the t(9;11)KMT2A::MLLT3 being the most recurrent (24/371, 6.5%), followed by t(10;11)KMT2A::MLLT10 (21/371, 5.7%), t(6;11)KMT2A::AFDN (10/371, 2.7%), t(11;19)KMT2A::ELL (6/371, 1.6%). In 14 patients, we found a NUP98 translocations (3.8%), and, in particular, 9 cases harbored the t(5;11)NUP98::NSD1 (2.4%, 5 of them together with a FLT3-ITD mutation), 4 the t(11;12)NUP98::KDM5A (1%) and only one case the t(2;11)NUP98::HOXD13 (0.3%). Other chromosomal aberrations were rarer in our cohort, with t(16;16)CBFA2T3::GLIS2 accounting for 2.4% of cases (9/371), t(6;9)DEK::CAN 1.3% (5/371, co-occurring with FLT3-ITD in 3/5 cases), t(1;22)RBM15::MKL1 1.1% (4/371), t(3;5)NPM1::MLF1 0.5% (2/371, one concomitant with FLT3-ITD), t(16;21)FUS::ERG 0.5% (2/371), t(16;21)RUNX1::CBFA2T3 0.3% (1/371), del(9)SET::NUP214 0.3% (1/371), t(8;16)KAT6A::CREBBP 0.3% (1/371), t(9;22)BCR::ABL1 0.3% (1/371). In addition, we retrospectively evaluated the incidence and prognostic relevance of mutations at specific loci of KIT, FLT3, ASXL1, WT1 and CEBPA genes. As concerns the KIT gene, we identified mutations at exon 8 or 17 in 16/371 AML (4.3%). Of note, all the 16 cases had a concomitant core-binding factor (CBF) rearrangement, and in particular 10/16 the t(8;21)RUNX1::RUNX1T1 translocation and 6/16 the inv(16)CBFB::MYH11, with a relative occurrence of 17% in the CBF-r AML subgroup (16 KIT mutated AML/94 CBF-r) and a slight, but not significant, impact on outcome. As regards exon 13 of ASXL1 gene and the tyrosine-kinase domain of FLT3 gene (FLT3-TKD), our study confirmed a low prevalence of these mutations, which occurred in 2.5% and 3.4% of AML respectively. On the contrary, WT1 mutations (exons 6-9) occurred in a consistent portion of AML (45 mutated cases, 13.2%)did not affect the outcome of FLT3-ITD mutated AML. Conversely, by screening both at bZIP and NTD domains of the CEBPA gene, we identified 18 double-mutated patients (4.8%), and notably all these patients had no other molecular marker detected at diagnosis, reducing the proportion of negative cases from 33% to 28%. We found that CEBPA mutated cases are characterized by a favorable outcome (EFS 93% vs 58% for CEBPA wt, p=0.008), this finding corroborating the indication to allocate these patients to the standard risk group.
Conclusion. Overall, in the prospective AIEOP AML2013/01 trial, we described the frequency of different molecular lesions and improved the genetic landscape of AML. The future use of NGS-based screenings could further optimize the characterization of the genetic landscape of childhood AML, thus refining the risk class patients stratification and modulation of treatment approaches.
Disclosures: Merli: Miltenyi: Speakers Bureau; Amgen: Speakers Bureau; Jazz: Membership on an entity's Board of Directors or advisory committees; Sobi: Membership on an entity's Board of Directors or advisory committees. Lo Nigro: Jazz Pharmaceutical: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Clinigen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Fagioli: Bluebird: Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Eusa Pharma: Consultancy; Iqone (Clinigen): Consultancy; Astellas: Speakers Bureau; Novartis: Consultancy; Takeda: Consultancy; Medac Pharma: Consultancy, Speakers Bureau; Bayer: Consultancy; Gilead: Consultancy. Rizzari: CLINIGEN, JAZZ, SERVIER, SERB: Consultancy, Honoraria, Speakers Bureau.